Opalina, 261 
sponds more or less closely in size and form and in number of con- 
tained granules to one of the chromosomes at the other end. These 
corresponding chromosomes are opposite to one another. ‘This all 
suggests very strongly that the daughter chromosomes in a dividing 
nucleus of Opalina are paired, just as truly as they are in a meta- 
zoan nucleus. 
We have already seen in the early telophase a condition which 
suggests that the chromosomes may be splitting longitudinally. The 
fate of the two halves that may be so formed is well-nigh impos- 
sible to follow, for the chromosomes almost at once unite to form a 
continuous ribbon. I have never found sixteen chromosomes at each 
end or even at one end, of a nucleus in the telophase, nor have I 
seen evidence that the chromatin ribbon is double. This, very in- 
teresting stage in the mitosis, needs further study, though I have 
little hope of obtaining conclusive results. At present we can only 
say that splitting cf the chromosomes does not occur at the equa- 
torial plate stage, that it may occur in the telophases, and that in 
the anaphases the daughter chromosomes seem to be paired as in 
metazoan mitoses. 
GonpDER believes that splitting of the chromosomes may often 
occur during the anaphases or telophases of maturation mitoses, but 
I know of no description of other mitoses in which the splitting of 
the chromosomes occurs after their distribution to the daughter 
nuclei instead of in the equatorial plate or in the prophases. 
If there be true splitting of the chromosomes in the telophase, 
one cannot be certain whether each granule in a chromosome divi- 
des (Fig. 86, Pl. XX). Some of the granules at the edges of the 
chromosome, seem spherical, others eliptical, others elongated rod- 
shaped, it is possible that adjacent granules often lie in contact, or 
even fuse, and so give an appearance of an elongated rod. In com- 
paring the two rows of granules at opposite edges of the apparently 
split chromosome, one sees a general resemblance but often the 
fusion or the contact of the granules in one line does not corre- 
spond exactly to that in the other line, and the two rows are not 
alike. Very likely, of course, even if the granules were all perfectly 
distinct, the two rows would not be found to be alike. 
Of course, if, in general in mitosis, chromosomes retain their in- 
dividuality during the spireme stage, is makes no real difference 
whether splitting of the chromosomes occurs before or during or 
after the spireme stage, so that mitosis in Opalina is not funda- 
mentally different from that in most Metazoa, if splitting of the 
18* 
